The major secretory proteins of the rat seminal vesicle are being developed as markers for the study of the mechanism by which androgens regulate protein synthesis in target organs. Current focus is on one of the smaller secretory proteins designated SVS IV. Emphasis in the coming year will be on preparation and cloning of recombinant bacterial plasmids that contain DNA copied from SVS IV messenger RNA. These plasmids will then be used as probes in hybridization assays so that we may quantitate SVS IV messenger RNA levels in animals at various stages of development and under various degrees of androgenic stimulation.